The present invention relates generally to containers for transporting fragile electronic components and, more particularly, to containers of the foregoing type which also serve to protect the components from damaging electrostatic influences.
Electronic components are typically transported from place to place in shipping containers specifically designed for protecting the fragile components from damaging shocks and the like. One known such container, see U.S. Pat. No. 3,273,779 to Mykleby, comprises a box-like carton having a hinged cover, the interior surfaces of the container's bottom and cover being lined with convoluted urethane foam. The urethane liners form a plurality of opposed and staggered foam fingers which firmly but gently hold or grip a component placed within the container when the cover is swung downwardly sandwiching the components between the opposed foam liners. Since the foam liners easily conform to the contours of the products placed within the container, economical packaging for irregularly shaped items and for multiple units is conveniently provided. Consequently, the need for elaborately constructed packages specially made to fit the particular shape of a product is largely eliminated.
While the above described shipping container, and other containers of similar construction, are suitable for use with certain product items, their suitability for use in transporting electrostatic sensitive electronic components is severely limited. More specifically, various electronic components such as metal oxide semiconductors (MOS), thick and thin film deposited products and others are highly sensitive to accumulations of electric charge, an excess accumulation of which may severely damage the the device. Precautions typically taken to minimize static electric discharges through the devices during transportation include the use of shorting rings to ground the leads of the device. Also, some devices or components are manufactured with built-in zener diodes to provide protection from low-energy sources.
Although the foregoing techniques are normally adequate to protect the transported components from harmful electrostatic influences, it is sometimes necessary to provide yet additional protection. Such additional protection frequently takes the form of a shipping enclosure commonly referred to as a Faraday cage. In its broadest sense, a Faraday cage may be defined as a system of conductors forming an essentially continuous conducting mesh or network about the object protected and including any conductors necessary for interconnection to the object protected and an adequate ground. In the past, the typical Faraday cage-type shipping enclosure has taken the form of an injection molded plastic container formed around a wire mesh screen in which the wire mesh screen forms an equipotential surface protecting the enclosed device from external electrostatic influences. In addition, the conductors forming the equipotential surface serve to dissipate any accumulation of electric charge built up on the enclosed devices by providing a conductive path between the devices and a source of ground potential.
The trasportation container of the present invention differs from those previously proposed in the provision and construction of a Faraday cage type enclosure which, in addition to providing improved electrical performance when compared to similar prior art structures, is embodied in a form particularly suited for protecting the enclosed components from damage resulting from physically disturbing or stressing the container.